Responding to another post got me thinking about the 25/2.8, and while the Oly 24/2.8 is well renowned ... it was my very first alt, so I didn't really even compare it with anything ... just going by recommendations / 16:9 world cup shootout ... but I don't recall the Zeiss being part of the final.

In the limited amount of time I have had to use it, I have found the the Zeiss 25/2.8 to be a decent performer. However the resolution definitely falls off in the corners wide open. It improves as it is stopped down, but maybe not as much as I would like.

The photo of the Provincial Legislative Assembly was taken @ f/8, and it seems to me that there is still a decrease in resolution in the corners when viewing @ 100%. I would say that it is not truly bad, but simply just not on par with some of the other lenses I have, such as the 35-70/3.4 or ZE 35/2. That is certainly not enough to keep me from using it though, especially since it has some other traits, such as when used wide open the center sharpness and overall contrast lends itself well to 3D 'pop'. (For example my last image when viewed at a larger size.) Mine is a MM, but made in Germany so I am not sure if the older and/or newer ones performed better in the corners. I got it for a good price, and at the time it filled the gap I had between 21mm & 35mm, that has since become a little more congested with my acquisition of the 28/2 'Hollywood'.

The ZF 25/2.8 has FC which affects the corners. The FC can be used to its advantage on some shots.
@Matt, we are all waiting for your 28/2 Hollywood shots. It will be interesting to see how it compares to the C/Y 28/2.8.
@Rustybug, Why not the ZE 21/2.8? Or is it out of the budget range?.

Kent, since you only have a 5D, I think the corner sharpness will be perfect at f/8, maybe even f/5.6 for some applications. It does show some CA (mostly blue/yellow), comparable to the Contax 28/2.8 I guess (meaning not much but noticeable if you're pixel peeping). The images have more bite to them than my Contax. Quite extreme actually. I like it much better than the more even, low contrast look of Zuikos.
These are my impressions from my tests with it on my 5D anyway.

Edit: helimat seems to be talking about the Contax 25/2.8. I assumed you were talking about the ZF25/2.8, Kent? What I wrote above is about the ZF.

Wayne, 21/2.8 ... budget, size, mustache ... but mostly, too close to 18mm for having BOTH. It's basically an either/or and the wider one wins this time.

The Oly 18/3.5 was a stretch for me as $$$ for a single piece of prime glass, but when you put all three issues in play on the 21, even if I could 'justify' it, it would still be working against my objectives. Total respect for it, just not for my bag.

Yes, I figure the FC that Zeiss likes to incorporate is probably more responsible for the 'soft corners' than them actually being 'soft'. I'm guessing that if you focused so that the corners were in focus, the center would look "soft" conversely ... anybody know if that is correct?

That might be why I'd go with both the Oly 24 and the 25 ... one for when the FC is too problematic, one for when it is advantageous.

Benjamin, +1 @ definitely a diff in drawing style between the Oly & Zeiss approach. They both have their place, which is why I'm not opposed to having both ... if the C/Y or ZF has it's own character that makes it worthy. It might come down to keeping the Oly 24 & C/Y 28/2.8 that I already have as an Oly/Zeiss 1-2 punch vs. going with the 25/2.8 (dowsizing the C/Y 28/2.8).

Actually, I had not yet distinguished between the C/Y and the ZF ... except for the C/Y's being more budget friendly, especially since I would be adapting the mount either way.

With the diff between Oly vs. Zeiss regarding CF ... what would you consider to be the worst / best application for CF? I can typically deal with the lower contrast of Oly in PP easy enough ... not so sure where I can / can't contend with CF.

Look up Edward's test of the ZF25 on his A900 if you want to see some examples of the corner performance.

Regarding FC: I have not owned the lens long enough to be able to say much about it, except that it can make a nervous, strained kind of bokeh outside the centre with close-ups. You can see this in the flower shots by the user "keira007". You'll most probably want to use your Nikkor 28/2.8 AI-s instead for close-ups.

Because you have the Contax 28/2.8 you should have a reasonable idea of the impact of FC on the ZF25 though. One difference is that the ZF25 focuses closer, which makes the FC more extreme (near MFD). My experience with the C/Y 28 is that when you back off to about one metre, the FC can contribute to the 3D effect and isn't really disturbing (example). When you're shooting a subject that fills most of the frame, you'll usually want to stop down to f/8 or so to mask the FC.

AFAIK the Contax 25 is usually said to be a slightly weaker than the 28, but the ZF25 probably beats both of them. I didn't like the smaller scale of detail in landscaped with it on my 5D though -- it seemed like too much was being blurred by the camera's AA filter.

I traded off Distagon 25/2.8 C/Y on behalf of Oly 24/2.8 for it's more even performance across the frame.Now consider buying 25/2.8 ZF.It is better in corners than 25/2.8 C/Y and - what is very important for me - it goes down to 17cm.

wayne seltzer wrote:
@Matt, we are all waiting for your 28/2 Hollywood shots. It will be interesting to see how it compares to the C/Y 28/2.8.

Sorry for the delay, at first I was negotiating a partial refund from the seller due to some cleaning marks on the front element, and then I had to go out of town for work. I am hoping to put it through the paces more thoroughly while I am on time off, but for the time being there I put up a few test shots on the C/Y thread, and there are a few more on my flickr page.

RustyBug wrote:
Hmmm, better corners & 17cm mfd with the ZF ... that could be meritable ... good enough to lighten the C/Y 28/2.8 from the bag ??

The corners are only better ate wide apertures. At f/8-11 you'll see no difference. I didn't find the 17cm MFD particularly useful with the ZF25 because of the funky field curvature that can make the bokeh rather unsightly. I know Lotusm50 disagrees, but I wouldn't buy this lens again to use it for close-ups. The ZF28/2 probably works better for close-ups, although I believe it also has FC (haven't seen examples though).

The C/Y 28/2.8 focuses close enough for my taste (25cm) and it's quite a bit compacter and lighter than the ZF25.

AhamB wrote:
The corners are only better ate wide apertures. At f/8-11 you'll see no difference. I didn't find the 17cm MFD particularly useful with the ZF25 because of the funky field curvature that can make the bokeh rather unsightly. I know Lotusm50 disagrees, but I wouldn't buy this lens again to use it for close-ups. The ZF28/2 probably works better for close-ups, although I believe it also has FC (haven't seen examples though).

The C/Y 28/2.8 focuses close enough for my taste (25cm) and it's quite a bit compacter and lighter than the ZF25.

+1
I never liked the nervous bokeh of the ZF 25 from the shots I have seen posted in this forum.
Wondering how the bokeh is on the CY 28/2.8 and 28/2 Hollywood?
z.* 28/2 has FC.

The 25/2.8 performs best at infinity, with perfect corners even wide open. The corners are better than the 35/2 and 50/1.4, and probably only beaten by the 21/2.8.

However, the corner sharpness deteriorates at closer distances due to FC, but depending on the subject it is possible to get perfectly sharp corner or two in the photo, as long as the subject is not planar.

I also fully agree with the comments about the bokeh. It can be very swirly and I prefer the bokeh of the Sony Zeiss 24/2 much more.

RustyBug wrote:
I just went back to 16:9 to check out the shootout with it and the Canon 24/1.4 L ... definitely was soft in the corners wide open, but started to come around @ 5.6 and by f8/11 seemed up to par.

The Canon 24/2.0 is supposed to kick ass on the 24/1.4L over all common apertures. At least in FD mount anyway. From what I was able to tell (not owning the 1.2L) this holds true. Is the 24/2.0 available in EF by any chance? Or are you using FD here?

So far, it sounds like the C/Y 28/2.8 should stay in the bag ... and maybe I should consider the 25 as an infinity specialist (funky bokeh & CF @ close range).

That would make the lineup:

Oly 18/3.5
Oly 24/2.8
C/Y 28/2.8
C/y 35-70/3.4

Sometimes we can split hairs regarding 3mm ... but is the diff between the 28 vs. the 25 THAT much, knowing that I've got the Oly 24 (albeit with a different drawing style) ... using the 24 & 28 more for drawing style variance option more so than FL difference (much like I've been using the Oly 21/3.5 & Nikon 20/2.8 AIS).

Bif ... FD's intrigue me, but I haven't gone down that road yet. I've still got Pentax, Rokkor, Leica, M42 waiting in line ahead of FD/FL I've never played with.

Speaking of Leica ... is there anything there that would make sense to bridge between the Oly 18 & the C/Y 35 ... in lieu of the Oly 24/2.8 & C/Y 28/2.8 ?